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Diamagnetic lanthanide tris β‐diketonates as organic‐soluble chiral NMR shift reagents
Author(s) -
Wenzel Thomas J.,
Wenzel Bradford T.
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20570
Subject(s) - chemistry , lanthanide , chirality (physics) , enantiomer , nmr spectra database , ligand (biochemistry) , cyclohexane , medicinal chemistry , organic chemistry , spectral line , nambu–jona lasinio model , quark , ion , biochemistry , chiral symmetry breaking , physics , receptor , quantum mechanics , astronomy
Diamagnetic lanthanium(III) and lutetium(III) tris β‐diketonate complexes of 3‐(trifluoroacetyl)‐ d ‐camphor, 3‐(heptafluorobutyryl)‐ d ‐camphor, and d , d ‐dicampholylmethane are shown to be effective chiral NMR shift reagents for determining the enantiomeric purity of compounds with hard Lewis base functional groups. These include substrates with amine, alcohol, epoxide, sulfoxide, and oxaxolidine moieties. Enantiomeric discrimination is observed in the 1 H NMR spectrum. Diamagnetic lanthanide complexes represent an alternative to paramagnetic varieties that often cause too much line broadening in the NMR spectra. The choice of which metal to use varies with substrate. Similarly, there is no consistent trend with ligand as not one of the complexes is consistently better than the others for all substrates. The enantiomeric discrimination also varies with solvent. Comparisons show that the chiral recognition was usually larger in benzene‐ d 6 than in chloroform‐ d or cyclohexane‐ d 12 . Chirality, 2009. © 2008 Wiley‐Liss, Inc.